Figure 5.

Decoding category choices from EEG-CSD data for object stimuli. A linear SVM classifier was used on averages of 80 ms windows with 20 ms time-steps (the average accuracy for all classifications within 100 ms time windows was tested using a permutation test; time point 0 = stimulus presentation). Decoding for A, 66.67 ms; B, 50.00 ms; C, 33.33 ms; and D, 16.67 ms target duration. Error bars indicate SEM. Significant time windows are highlighted. E, Independent temporal pattern classification using data within each 80 ms window for each channel separately. Scalp maps show decoding accuracy for selected times corresponding to onset and peaks in spatial decoding (highest discriminability). During early stages, mostly occipital and parietal electrodes encoded choices (P7, P5, PO7, PO9, P6, P8, FC4, all p < 0.01; PO8, Oz, all p < 0.05; O2, p = 0.07). Similar channels were predictive during the first peak (POz, Oz, all p < 0.001; P7, PO7, PO9, P6, PO8, O2, all p < 0.05; F6, p = 0.05; P5, p = 0.06; PO4, p = 0.08). During the second peak prefrontal electrodes and parietal channels were predictive (FT8, PO4, all p < 0.01; Fp1, F8, all p < 0.05; PO8, p = 0.07).